Abstract: Propositions are usually taken to help explain the behavior of rational agents. However, a closer look at signaling games suggests otherwise: rational agents often acquire partial beliefs, and many of their signals are ambiguous. Signaling games also suggest that it is rational for agents to mix their behavior in response to partial beliefs and ambiguous signals. But as I show in this talk, propositions cannot help explain the mixing behavior of rational agents. My suggestion is that we should abandon propositions in explanations of rational behavior and adopt instead a probabilistic notion of content.